1. Field of the Invention
The invention relates to an apparatus for determining the fuel consumption prevailing at each instant of operation of an internal combustion engine of a motor vehicle. More particularly, the invention relates to such apparatus which comprises a device which supplies an electrical signal indicative of the instantaneous rate of fuel use of the engine, and further comprises devices which supply data on the number of revolutions of the engine and the distance covered, and an indicator stage to which the signals are fed and which determines and indicates the fuel consumption with reference to a distance unit.
2. Prior Art
As is known, in a diesel injection pump there is an internal metering element which moves so as to balance or mediate between the call for a certain level of injection of fuel, received from a movable control rod connected to an external accelerator pedal or throttle lever, and the call for a different level of fuel injection determined by the engine speed. For example, when a diesel engine automobile is descending a steep grade, the internal metering element will deliver less fuel to the engine, for the same setting of the accelerator pedal, than when the automobile is running steadily on the level.
The internal metering element of the injection pump of diesel engines is suited as a mechanical control unit whose motion can supply an electrical signal indicative of fuel conveyed per cycle of the engine. Therefore, it is already known to connect a remote position indicator to the internal metering element, as disclosed in German laid-open patent application DE-OS No. 24 40 398, in order to employ the data thereof for fuel consumption measurement. This, however, is not possible without substantial expense, since the internal metering element is positioned inside the injection pump, and the access to it is therefore very difficult. Upon opening up or modification of the injection pump, damage must be expected which results in a deterioration of its efficiency. Besides, it is difficult to find a transmitter insensitive to shock and temperature which can be located in the engine chamber and which can tolerate the environment prevailing therein and remain accurately adjusted even after long service.